[Pablo68]

Here is a not very scientific but comparative of all 4 variations of engine. All on idle, all under the bonnet, so no audio trickery, no exhausts, no sweet spot in the rev range:

N47 (4 pot diesel - eg 320D/325D) engine idle:

N57 (6 pot diesel - eg 330D/335D) engine idle:

N20 (4 pot petrol - eg 320i/328i) engine idle:

N55 (6 pot petrol - eg 335i) engine idle:

[ukbeemerboy]

A 6 will always be smoother than a 4.... Bit unfair showing the 4 pot diesel with the bonnet up and the 6 pot running with it shut though!

[Steve C]

Both 6cyl sound good, both 4cyl sound horrible. Surprised as I thought the two petrol engines would be better than the two diesel engines.

[Pablo68]

Originally Posted by ukbeemerboy

A 6 will always be smoother than a 4.... Bit unfair showing the 4 pot diesel with the bonnet up and the 6 pot running with it shut though!

All I could find at short notice, but I agree the N57 video should have the bonnet up so it doesn't mute the high frequency overtones

[HighlandPete]

As said not too scientific, wonder how the audio levels really compare against each other? No way to judge unless they have one controlled source.

Pleased to say my N55 is much sweeter than the example video. It does appear to have very loud injectors. Reminds me of a Honda 1600 TC engine I once had, very loud injection... still does... in my nephew's original Mini "transplant" installation.

HighlandPete